In a general practitioner's list of 2000 people 40 to 50 will have a first degree relative with cancer, 10 of which relatives will have developed cancer under the age of 50 years. A few of these people will have a strong inherited predisposition to some common cancers, such as breast and ovarian cancer.1 Mutations in the recently identified BRCA1 gene are associated with extremely high lifetime risks of cancer of the breast (87%) and ovaries (44%).2 These mutations account for an estimated 10-30% of all women diagnosed with breast cancer under the age of 45,34 an important group as they contribute a large proportion of the years of life lost to breast cancer

Individuals should have access to accurate information about their risk, and those at high risk want access to effective screening.5 But our ability to identify women at high risk has come at a time …